I know this is an old thread, but had to jump in to share my two satoshis. I am by far a supporter of bitcoin over all other types of cryptocurrency, but there are a couple others out there that have legit utility as well as upside potential investment wise. I think Monero is the second most legit crypto coin. Truly private transactions is pretty bad ass, though I don't think that's how bitcoin should ever be (number or reasons). Litecoin is nice for quick and cheap transactions. I know Ethereum is centralize and a total shitcoin and what not, but I do still see a sizable bit of upside in that coin.
If we talk about privacy and usage purposes, you are right that there are only a few cryptocurrencies apart from Bitcoin that are private, decentralized, and secure. However, if we see from an investment perspective, there can be many more that one can use for short-term investment purposes to earn a small percentage of profit on every trade.
Talking about Ethereum, it might be centralized, but we can't ignore the fact that thousands of projects in the industry are running on top of Ethereum blockchain which makes it one of the most trusted cryptocurrencies in the industry which makes it a good option for investment. There are many more, a small research and you can find a bunch.
You have many points that align with mine, but I have to say that you confused me with a few of your points, perhaps, they are merely mistakes. One of them is the Ethereum remark of being a centralised cryptocurrency. This can only be a mistake, or maybe you should clarify that to avoid people, particularly the newbies mistaking it for something else.
Regardless, you are saying what is right, Bitcoin has a whole lot of good functions and reasons for anyone to want to invest in it. But at the same time, we look beyond this, this is even as the investment purpose is the main goal here unless people fake it. If I ask you, why do you think that people are investing their money in Bitcoin and other cryptocurrencies, is it not for the money? That is why money is the number one priority here, then decentralization, safety and others will be secondary. Many people who were talking alone about Bitcoin before on the forum are now talking about altcoins as well as ways to invest their money. While many will continue to fake it in the open but are actually investing heavily in altcoins.
Owning to this, one should know that our agenda and purpose for dealing with cryptocurrency is the money, and when there are many alternatives to Bitcoin that can earn investors multiple of what Bitcoin would earn in just the same period of time, won't they wisely and smartly opt for them? I think this settles it. This is unless the person is just a core ardent supporter of Bitcoin and an extremist about it. And this set of people are the ones who bought it when it was so cheap, so what do you expect?